# Unit 3 Extra Credit

Either print this page and complete or (better yet) neatly show your answers on a separate page of paper. All answers must be expressed as complete sentences and/or all work shown to receive credit.

1. A boat that can travel at 4 m/sec in still water is heading straight across a river. The river current is 3 m/sec. The river is 320 meters wide.

a. At what angle to the shore does the boat actually travel? Use a vector diagram.

b. What is the speed of the boat as seen from the shore? PSYW

c. What time does it take the boat to cross the river if there is no current? PSYW

d. What time does it take the boat to cross the river if there is a current? PSYW

e. How far downstream is the boat when it reaches the other side with the current present? PSYW

2. An airplane has a heading of 340° and an air speed of 300 mph. The wind is blowing at 100 mph in a direction of 130°. Using a vector diagram, determine the resulting velocity (speed and direction) of the airplane.

3. A student threw a ball horizontally out of a second story window. It was caught by another student who was 10.0 meters away and 8.0 meters below the original position of the ball. What was the initial velocity of the ball? PSYW

4. A camper dives from the edge of a swimming pool at water level with a speed of 8.0 m/sec at an angle of 30 degrees above the horizontal.

a. How long a time is the diver in the air?

b. How far upward does the diver travel?

c. How far out into the pool does the diver land?

Resources for physics students are available through links on the GBS Physics Home Page. Such resources include the Multimedia Physics Studios (a collection of animations and movies which illustrate key physics concepts) and The Physics Classroom (an online tutorial written in an easy-to-understand language).